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3 years ago

In some plants, the pistils don’t Form until a few days after the stamens do.How might this keep a plant from self pollinating

1 answer:

3 0

For a flower to be pollinated, pollen from an anther (which is located at the top of the stamen) needs to reach a stigma (at the top of the pistle.) Some plants are genetically capable of pollinating themselves if their own pollen reaches their own stigma; some plants are not capable of self pollination under any circumstances.

For plants that can genetically self pollinate, but would prefer not to, they can avoid this by having their pistil and pollen/stamens mature at different times. If the stamens mature first, the pollen will be dispersed by animals or wind or whatever dispersal mechanism it relies on. Then by the time the pistil is ready to be pollinated, there is no pollen left in that flower to land on the stigma.

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An astronaut on an alien planet drops a rock into a crater which is 100 meters deep. The rock hits the bottom of the crater 4 se

Semmy [17]

Answer:

The gravity on this planet is stronger than that of earth.

Explanation:

First we need to find the acceleration due to gravity value of this planet to compare its gravity force with that of the earth. Hence, we will use second equation of motion:

h = Vi t + (0.5)gt²

where,

h = height or depth of crater = 100 m

Vi = Initial Velocity of rock = 0 m/s

t = time = 4 s

g = acceleration due to gravity on this planet = ?

Therefore,

100 m = (0 m/s)(4 s) + (0.5)(g)(4 s)²

g = (200 m)/(16 s²)

g = 12.5 m/s²

on earth:

ge = 9.8 m/s²

Since,

ge < g

Therefore,

The gravity on this planet is stronger than that of earth.

6 0

3 years ago

When an electron falls from a higher to a lower energy level in an atom, the photon released has a wavelength of 121.6 nm. What

yarga [219]

Answer:

$\Delta E=1.64*10^{-18}J$

Explanation:

The energy difference between the energy levels involved in the transition of the electron is directly proportional to the frequency of the emitted photon:

$\Delta E=h\nu(1)$

Where h is the Planck constant. The photon's frequency is inversely proportional to its wavelegth:

$\nu=\frac{c}{\lambda}(2)$

Here c is the speed of light. Replacing (2) in (1):

$\Delta E=\frac{hc}{\lambda}\\\Delta E=\frac{(6.63*10^{-34}J\cdot s)(3*10^8\frac{m}{s})}{121.6*10^{-9}m}\\\Delta E=1.64*10^{-18}J$

6 0

2 years ago

The rubber band contains .......potential energy as it is stretched.

kodGreya [7K]

Answer:

elastic potential energy

You input potential (stored) energy into the rubber band system when you stretched the rubber band back. Because it is an elastic system, this kind of potential energy is specifically called elastic potential energy.

Explanation:

4 0

1 year ago

If the units of your answer are kg ∙ m2/s3, which of the following types of quantities could your answer be?

kirza4 [7]

Answer:

D. power

Explanation:

kg represents mass

(m/v)² represents velocity squared

Then kg·m²/s² represents mass·velocity² = kinetic energy or potential energy or work.

kg·m²/s³ will be the rate of doing work, which is power

4 0

2 years ago

Read 2 more answers

What are the two main types of energy?

djyliett [7]

Answer:

Fourth option

Explanation:

They're many different types of energy, from chemical and mechanical to heat and solar energy. But the two most basic types of energy are "kinetic and potential energy" or the fourth option. Kinetic energy is the energy an object has when it is in motion, while potential energy is the energy an object has when it's as rest. These two specific types of energies are the most basic and you can even convert them into many different types of energies, like heat or electrical energy.

Hope this helps.

7 0

2 years ago